CDC Principles of Epidemiology - Lesson 3

Question 1

Proportionate mortality

Answer 1

Formula: Proportionate Mortality = (Deaths caused by a particular cause / Total deaths in the population) * 100%
Represents: The proportion of deaths in a specified population over a period of time attributable to different causes.

Question 2

Ratio

Answer 2

Formula: Ratio = Comparison of two quantities that have the same units of measurement.
Represents: A comparison of two quantities that have the same units of measurement.

Question 3

Proportion

Answer 3

Formula: Proportion = A ratio that compares a part to a whole.
Represents: A ratio that compares a part to a whole.

Question 4

Rate

Answer 4

Formula: Rate = A ratio with different units of measurement.
Represents: A ratio with different units of measurement.

Question 5

Incidence

Answer 5

Formula: Incidence = The occurrence of new cases of disease in a population in a given period of time.
Represents: The occurrence of new cases of disease in a population in a given period of time.

Question 6

Incidence Proportion or Attack Rate

Answer 6

Formula: Incidence Proportion = (Number of new cases of disease / Size of the population at the start of the period) * 100%
Represents: The proportion of a population that develops the disease during a specific period.

Question 7

Incidence Rate (or Person-Time Rate)

Answer 7

Formula: Incidence Rate = (Number of new cases of disease / Total time each person was observed) per person.
Represents: A measure of incidence that incorporates time into the denominator.

Question 8

Prevalence Rate

Answer 8

Formula: Prevalence Rate = (All new cases and pre-existing cases during a given time period / Population during that time period) * 100%
Represents: The proportion of people in a population who have a specific disease at a specified point in time or over a specified period of time.

Question 9

Mortality Rate

Answer 9

Formula: Mortality Rate = (Deaths occurring over a specific time period / Size of the population among which the deaths occurred) * 1000 (commonly)
Represents: The measure of the frequency of occurrence of death in a defined population during a specified time interval.

Question 10

Crude Mortality Rate

Answer 10

Represents: Mortality rate from all causes of death for a population.

Question 11

Cause-specific Mortality Rate

Answer 11

Represents: Mortality rate from a specific cause.

Question 12

Age-specific Mortality Rate

Answer 12

Represents: Mortality rate limited to a specific age group.

Question 13

Infant Mortality Rate

Answer 13

Formula: Infant Mortality Rate = (Number of deaths among children < 1 year of age / Number of live births) * 1,000 (commonly)
Represents: The rate of death among infants under one year of age.

Question 14

Neonatal Mortality Rate

Answer 14

Formula: Neonatal Mortality Rate = (Number of deaths among children under 28 days of age / Number of live births) * 1,000 (commonly)
Represents: The rate of death among neonates.

Question 15

Postneonatal Mortality Rate

Answer 15

Formula: Postneonatal Mortality Rate = (Number of deaths among children aged from 28 days to 1 year / Live births in the same time period) * 1,000 (commonly)
Represents: The rate of death among children aged from 28 days to 1 year (non-inclusive).

Question 16

Maternal Mortality Rate

Answer 16

Represents: Mortality of maternal mothers.

Question 17

Sex-specific Mortality Rate

Answer 17

Represents: Mortality rate of one sex.

Question 18

Race-specific Mortality Rate

Answer 18

Represents: Mortality rate of one race.

Question 19

Death-to-Case Ratio

Answer 19

Formula: Death-to-Case Ratio = (Number of deaths attributed to a particular disease during a specified time period / Number of new cases identified of that disease during the same time period) * 100%
Represents: The ratio of deaths to new cases of a particular disease during a specified time period.

Question 20

Case-fatility Rate

Answer 20

Formula: Case-Fatality Rate = (Number of deaths from that case / Number of cases) * 100%
Represents: The proportion of people with a particular condition who die from that condition.

Question 21

Natality Measures

Answer 21

Represents: Population-based measures of birth.

Question 22

Risk Ratio or Relative Risk

Answer 22

Formula: Risk Ratio = (Risk of disease in the group of primary interest / Risk of disease in the comparison group)
Represents: Compares the risk of a health event among one group with the risk among another group.

Question 23

Rate Ratio

Answer 23

Formula: Rate Ratio = (Rate for the group of primary interest / Rate for the comparison group)
Represents: Compares incidence rates, person-time rates, or mortality rates of two groups.

Question 24

Odds Ratio

Answer 24

Formula: Odds Ratio = (AD/BC)
Represents: A measure of the relationship between an exposure with two categories and health outcome.

Question 25

Attributal Proportion

Answer 25

Formula: Attributable Proportion = ((Risk for exposed group - risk for unexposed group) / Risk for exposed group) * 100% Represents: A measure of the public health impact of a causative factor.

Question 26

Vaccine efficacy or effectiveness

Answer 26

Formula: Vaccine Efficacy = (Risk among unvaccinated group - Risk among vaccinated group / Risk among unvaccinated group) Represents: The proportionate reduction in cases among vaccinated people.

Question 27

YPLL

Answer 27

- Calculation from line listing Decide on end point Exclude all people who died at or after the endpoint Calculate YPLL for all people who died before the end point by subtracting the age at death from the end point YPLLIndividual = endpoint - age of death Sum the individual YPLLs - Calculation from a frequency Eliminate all age groups older than the endpoint For each age group left, identify the midpoint of the group Youngest + oldest + 1 / 2 Identify the YPLL of all ages younger than the endpoint by subtracting the midpoint from the endpoint Calculate age-specific YPLL by multiplying the age group’s YPLL times then number of people in that age group Sum these YPLLs

Question 28

YPLL Rate

Answer 28

YPLL / population under the endpoint